Re-initialise field on setClasspathWithout that change, it became illegal to do something like`setClasspath(files(someFile, getClasspath())` which can be used toprepend values to the classpath.Fixes #8748
Re-initialise field on setClasspathWithout that change, it became illegal to do something like`setClasspath(files(someFile, getClasspath())` which can be used toprepend values to the classpath.Fixes #8748
Re-initialise field on setClasspathWithout that change, it became illegal to do something like`setClasspath(files(someFile, getClasspath())` which can be used toprepend values to the classpath.Fixes #8748
Restore JavaExecHandleBuilder.classpath contractThe contract is to append the passed in parameters to the existingclasspath. This was broken in refactoring and instead would behave as ifJavaExecHandleBuilder.setClasspath had been called.Issue #8748